Peak Demand Forecasting Calculator

The engine adds Base Growth Rate plus EV Load Growth and subtracts Efficiency Reduction to get one net annual growth rate, then compounds that single rate over the forecast period — it's mathematically equivalent to netting the two effects against organic growth every year rather than modeling them as separate curves. This keeps the compounding formula simple, but it also means the calculator can't show you, say, how much of the forecast peak is attributable to EVs specifically versus base growth; you'd need to re-run it with EV Load Growth set to 0 to isolate that effect.

Forecast Peak is simply the projected MW demand at the end of the forecast period, but Required Capacity multiplies that figure by (1 + Reserve Margin) to add a cushion above expected demand. Utilities plan this cushion in so there's still enough generation and transfer capability available if a plant trips offline unexpectedly, weather drives demand higher than forecast, or the load forecast itself understates growth.

Yes — if Efficiency Reduction exceeds the sum of Base Growth Rate and EV Load Growth, the net growth rate becomes negative, and the same compound formula (current peak times (1 + net rate) raised to the forecast years) correctly produces a shrinking Forecast Peak over time. This is a legitimate scenario for a territory with aggressive efficiency programs or a shrinking population, and the calculator doesn't floor the result at zero growth.

The model assumes EV penetration and efficiency gains are flat annual percentages applied every year of the forecast, but real EV adoption typically follows an S-curve — slow uptake, a period of rapid growth, then saturation — rather than a constant rate indefinitely. Over a short 5-10 year horizon that simplification barely matters, but compounded over 20-30 years the error can grow substantially, so long-horizon results here are best treated as directional planning inputs rather than numbers to build a specific capacity investment decision on.